ANDROID: kbuild: merge module sections with LTO

LLD always splits sections with LTO, which increases module sizes. This
change adds a linker script that merges the split sections in the final
module.

Bug: 145297228
Change-Id: I247e8bd029bd0f98a4fa1cd4db7f6398467b8e55
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>